U.S. patent application number 11/053580 was filed with the patent office on 2006-08-10 for banded door sill base and door sill assembly, and method of forming same.
Invention is credited to Robert H. Young.
Application Number | 20060174545 11/053580 |
Document ID | / |
Family ID | 36778493 |
Filed Date | 2006-08-10 |
United States Patent
Application |
20060174545 |
Kind Code |
A1 |
Young; Robert H. |
August 10, 2006 |
Banded door sill base and door sill assembly, and method of forming
same
Abstract
The present invention is directed to a banded doorsill base for
disposition between a pair of doorjambs of a door frame. The
doorsill base includes an elongate central portion formed from a
polymeric material having a first coefficient of linear expansion,
and first and second wooden strips bonded to and extending along
opposite sides of the central portion for constraining the central
portion and preventing linear expansion thereof. The first and
second strips are formed from a material having a second
coefficient of linear expansion less than the first coefficient.
The first and second strips substantially prevent linear expansion
of the central portion. The present invention also relates to a
method of forming the banded doorsill base, and to a doorsill
assembly having a banded doorsill base.
Inventors: |
Young; Robert H.; (Beaver
Dam, KY) |
Correspondence
Address: |
BERENATO, WHITE & STAVISH, LLC
6550 ROCK SPRING DRIVE
SUITE 240
BETHESDA
MD
20817
US
|
Family ID: |
36778493 |
Appl. No.: |
11/053580 |
Filed: |
February 9, 2005 |
Current U.S.
Class: |
49/468 |
Current CPC
Class: |
E06B 1/70 20130101; E06B
2001/707 20130101 |
Class at
Publication: |
049/468 |
International
Class: |
E06B 1/70 20060101
E06B001/70 |
Claims
1. A banded doorsill base for disposition between a pair of door
jambs of a door frame, the doorsill base comprising: an elongate
central portion formed from a material having a first coefficient
of linear expansion, said central portion having first and second
opposite sides; a first strip attached to and extending along said
first side; and a second strip attached to and extending along said
second side, said first and second strips formed from a material
having a second coefficient of linear expansion less than the first
coefficient, said first and second strips substantially
constraining linear expansion of said central portion.
2. The doorsill base of claim 1, wherein said central portion is
formed from a material selected from the group consisting of a
polymer and a wood fiber-resin composite.
3. The doorsill base of claim 2, wherein said central portion is
formed from polyvinyl chloride.
4. The doorsill base of claim 2, wherein said central portion is
formed from a material having a coefficient of linear expansion of
between about 1.8.times.10.sup.-5 in/in/.degree. F.
5.times.10.sup.-5 in/in/.degree. F.
5. The doorsill base of claim 1, wherein said first and second
strips are formed from a material selected from the group
consisting of hardwood, softwood, and metal.
6. The doorsill base of claim 1, wherein said central portion
includes an interiorly disposed planar surface adjacent said first
strip and an exteriorly disposed sloped portion adjacent said
second strip.
7. The doorsill base of claim 6, wherein said planar surface is
recessed from said sloped portion.
8. The doorsill base of claim 7, wherein said first strip is a shoe
strip having an upwardly extending wall relative said planar
surface.
9. The doorsill base of claim 7, further comprising at least one
weep channel extending downwardly from said planar surface through
said sloped portion and through said second strip.
10. The doorsill base of claim 9, wherein said weep channel extends
substantially perpendicular to said second strip.
11. The doorsill base of claim 9, wherein said weep channel
includes a bottom surface having an arcuate configuration.
12. The doorsill base of claim 1, wherein said first and second
strips are adhesively bonded to said central portion.
13. The doorsill base of claim 12, wherein said first and second
strips are adhesively bonded to said central portion using one of a
water-curing PUR adhesive and a hot-melt PUR adhesive.
14. A doorsill assembly, comprising: a base having an elongate
polymer central portion having a first coefficient of linear
expansion and first and second outer strips secured to opposite
longitudinal edges of said central portion, said outer strips
formed from a material having a second coefficient of linear
expansion less than the first coefficient, said outer strips
substantially constraining linear expansion of said central
portion; an elongate threshold member disposed over and connected
to said base; and an elongate cover panel connected to and
overlying a portion of said base.
15. The doorsill assembly of claim 14, wherein said central portion
is formed from a material selected from the group consisting of a
polymer and a wood fiber-resin composite.
16. The doorsill assembly of claim 15, wherein said central portion
is formed from polyvinyl chloride.
17. The doorsill assembly of claim 14, wherein said first and
second outer strips are formed from a material selected from the
group consisting of hardwood, softwood, and metal.
18. The doorsill assembly of claim 14, wherein said central portion
includes an interiorly disposed planar surface adjacent said first
outer strip and an exteriorly disposed sloped portion adjacent said
second outer strip.
19. The doorsill assembly of claim 18, wherein said cover panel
overlies and extends from said sloped portion to said second outer
strip.
20. The doorsill assembly of claim 18, wherein said first outer
strip is a shoe strip having an upwardly extending wall relative
said planar surface.
21. The doorsill assembly of claim 18, further comprising at least
one weep channel extending downwardly from said planar surface
through said sloped portion and through said second strip.
22. The doorsill assembly of claim 21, wherein said cover panel
includes a slot aligned with said weep channel.
23. The doorsill assembly of claim 22, wherein said threshold
member includes a drain channel extending from opposite ends
thereof, said threshold member having slots at said opposite
ends.
24. The doorsill assembly of claim 14, wherein said first and
second outer strips are adhesively bonded to said central
portion.
25. A banded doorsill base for disposition between a pair of door
jambs of a door frame, the doorsill base comprising: an elongate
central portion formed from a polymeric material having a first
coefficient of linear expansion, said central portion having first
and second opposite sides; a first wooden strip attached to and
extending along said first side; and a second wooden strip attached
to and extending along said second side, said first and second
wooden strips having a second coefficient of linear expansion less
than the first coefficient, said first and second wooden strips
constraining said central portion and substantially preventing
linear expansion thereof.
26. A method of forming a banded doorsill base, comprising the
steps of: providing a central portion formed from one of a polymer
material and a wood fiber-resin composite and having a first
coefficient of linear expansion; adhesively bonding a first wood
strip to a first edge of the central portion; and adhesively
bonding a second wood strip to a second edge of the central portion
opposite the first edge, the first and second wood strips having a
second coefficient of linear expansion less than the first
coefficient so that the first and second wood strips substantially
constrain linear expansion of the central portion.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to a banded doorsill base
for disposition between a pair of door jambs of a door frame. The
doorsill base includes an elongate central portion formed from a
polymeric material having a first coefficient of linear expansion,
and first and second wooden strips bonded to and extending along
opposite sides of the central portion for constraining the central
portion and preventing linear expansion thereof. The first and
second strips are formed from a material having a second
coefficient of linear expansion less than the first coefficient.
The first and second strips substantially prevent linear expansion
of the central portion. The present invention also relates to a
method of forming the banded doorsill base, and to a doorsill
assembly having a banded doorsill base.
BACKGROUND OF THE INVENTION
[0002] Doorsill assemblies have been used for many years to seal
the bottoms of swinging doors when they are in the closed position.
Many sill assemblies include an aluminum threshold member that is
secured to a wooden base plate. The assembly is secured to the
lower side of a door frame between a pair of door jambs.
[0003] Wooden base plates are often used because they are easy to
install and relatively inexpensive. In addition, wood has a
relatively low thermal conductivity and high dimensional stability.
However, wooden base plates are subject to degradation from wood
rot. As such, door sill manufacturers have attempted to find an
alternative to wooden base plates.
[0004] Various attempts to form a door sill base from alternative
materials, such as foam plastics, and polymer/wood fiber
composites, have been made. However, resinous materials exhibit a
relatively high coefficient of linear expansion. The length of a
base plate formed from such resinous materials therefore fluctuates
as temperature fluctuates. This, in turn, may result in a poor fit
between the base plate and the door frame, particularly with door
sills having a length of six feet or more. Therefore, non-wooden
base plates have not proven practical or cost efficient.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to a banded doorsill base
for disposition between a pair of doorjambs of a door frame. The
doorsill base includes an elongate central portion, and first and
second strips. The central portion is formed from a material having
a first coefficient of linear expansion, and has a generally
rectangular configuration in plan view with first and second
opposite sides and first and second opposite ends. The first strip
is attached to and extends along the first side of the central
portion. The second strip is attached to and extends along the
second side of the central portion. The first and second strips are
formed from a material having a second coefficient of linear
expansion less than the first coefficient. The first and second
strips constrain the central portion and substantially prevent
linear expansion of the central portion.
[0006] The present invention also relates to a doorsill assembly.
The assembly includes a base having ah elongate polymer central
portion having a first coefficient of linear expansion. First and
second outer strips are secured to opposite longitudinal edges of
the central portion. The outer strips are formed from a material
having a second coefficient of linear expansion less than the first
coefficient. The outer strips constrain the central portion and
substantially prevent linear expansion of the central portion. The
assembly also includes an elongate threshold member disposed over
and connected to the base, and an elongate cover panel connected to
and overlying a portion of the base.
[0007] A method of forming a banded doorsill base is disclosed. A
central portion formed from one of a polymer material and a wood
fiber-resin composite and having a first coefficient of linear
expansion is provided. A first wood strip is adhesively bonded to a
first edge, of the central portion. A second wood strip is
adhesively bonded to a second edge of the central portion opposite
the first edge. The first and second wood strips have a second
coefficient of linear expansion less than the first coefficient so
that the first and second wood strips substantially prevent linear
expansion of the central portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of a banded doorsill base
according to an embodiment of the present invention;
[0009] FIG. 2 is an elevational view of the banded doorsill base
shown in FIG. 1;
[0010] FIG. 3 is a cross-sectional view of a doorsill assembly
according to a first embodiment;
[0011] FIG. 4 is an exploded assembly drawing of the doorsill
assembly shown in FIG. 3;
[0012] FIG. 5 is a cross-sectional view of a doorsill assembly
according to a second embodiment; and
[0013] FIG. 6 is a fragmentary exploded assembly drawing of the
doorsill assembly shown in FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0014] A banded doorsill base 10 according to an embodiment of the
present invention is best shown in FIGS. 1 and 2. Base 10
preferably has a suitable length for disposition between a pair of
doorjambs of a door frame. Base 10 includes an elongate central
portion 12 preferably formed from a polymer material, such as
foamed polyvinyl chloride, foamed urethane, and polystyrene.
Alternatively, central portion 12 may be formed from a wood
fiber-resin composite, such as a polyethylene-wood flour
composite.
[0015] The material used to form central portion 12 has a known
coefficient of linear expansion. The coefficient of linear
expansion is defined as the change in length of a substance per
change in temperature. Stated mathematically, the coefficient of
linear expansion a may be calculated as follows: .DELTA. .times.
.times. L L 0 = .alpha. .times. .times. .DELTA. .times. .times. T
##EQU1## where .DELTA.L is the change in length, L.sub.0 is the
initial length of the object, and .DELTA.T is the change in
temperature.
[0016] A suitable material for forming central portion 12 will have
a coefficient of linear expansion of between about
5.times.10.sup.-5 in/in/.degree. F. (e.g. urethane foam) and about
1.8.times.10.sup.-5 in/in/.degree. F. (e.g. wood fiber-resin
composite). Generally, as the coefficient of linear expansion
increases within this suitable range, the width of central portion
12 should decrease in order to avoid bowing of the ends.
[0017] Central portion 12 preferably has a generally rectangular
configuration in plan view with first and second opposite sides 14,
16 and first and second opposite ends 18, 20. A first strip 22 is
secured to first side 14 and extends from first end 18 to second
end 20. A second strip 24 is secured to second side 16 and extends
from first end 18 to second end 20. Preferably, first and second
strips 22, 24 are adhesively bonded to central portion 12. I have
found that a water-curing polyurethane (PUR) adhesive provides a
sufficiently strong adhesive bond, though other adhesives may be
used, including hot-melt PUR adhesives. A suitable water-curing PUR
adhesive is available from National Starch & Chemical Company
of Bridgewater, New Jersey under number 82-4000. Alternatively,
first and second strips 22, 24 may be mechanically secured to
central portion using fasteners, such as screws, nails, pins, or
some other suitable fastener.
[0018] First and second strips 22, 24 are preferably formed from
hardwood, preferably a stain grade hardwood such as oak, but may
also be formed from softwood, such as pine. However, hardwood is
stronger compared to softwoods and therefore provides additional
strength and structural integrity to the resulting banded base 10.
In addition, the surface of hardwood has a relatively high bond
shear strength compared to softwood, typically about five times
greater than the shear strength of softwood. Alternatively, first
and second strips 22, 24 may be formed from metal or some other
material having a relatively low coefficient of thermal
expansion.
[0019] The material used to form first and second strips 22, 24
(e.g. hardwood and metal) exhibits minimal expansion due to
temperature fluctuations. Strips 22, 24 have a relatively low
coefficient of linear expansion, typically about 0.05 to about 0.1
that of the polymer central portion 12. For example, the linear
expansion of wood due to normal temperature fluctuations is
typically only about 0.1% to 0.2%. First and second strips 22, 24
are secured to central portion 12 and constrain central portion 12
such that linear expansion of central portion 12 is substantially
prevented. The adhesive bond or mechanical fastener securing strips
22, 24 to central portion 12 is greater than the force generated by
the constrained expansion of central portion 12 due to temperature
fluctuations. In this way, strips 22, 24 counterbalance the force
generated by the attempted expansion of central portion 12, thereby
substantially restraining any such expansion. This, in turn,
ensures a good fit of base 10 between door jambs, even with
temperatures fluctuations. I have found that strips 22, 24 are
required along the opposite sides 14, 16. If only one side is
constrained by a wood strip, then the unconstrained side will
expand and thereby tend to bow base 10.
[0020] Depending on the material used to form central portion 12,
central portion 12 may undergo a minimal amount of linear
expansion, which creates a slightly bowed appearance to ends 18,
20. However, such expansion is minimal and does not effect the
installation and/or fit of base 10 between corresponding
doorjambs.
[0021] As best shown in FIG. 2, central portion 12 may include an
interiorly disposed planar surface 26 adjacent first strip 22 and
an exteriorly disposed sloped portion 28 adjacent second strip 24.
Planar surface 26 is recessed from sloped portion 28. An interface
wall 27 extends between and interconnects planar surface 27 and
sloped portion 28. Sloped portion 28 preferably includes a groove
29 spaced from and parallel to interface wall 27. Groove 29 may be
configured for receiving a rib on a cover panel of a doorsill
assembly. First strip 22 is preferably a shoe strip having an
upwardly extending wall 22a relative to planar surface 26.
[0022] As best shown in FIG. 1, base 10 may include one or more
weep channels 30, which extend downwardly from planar surface 26
through sloped portion 28 and second strip 24. For example, base 10
may include a pair of weep channels 30 proximate opposite ends 18,
20. Weep channels 30 preferably extend substantially perpendicular
to second strip 24. The bottom surface of each weep channel may
have either a planar configuration, angling downwardly, or an
arcuate configuration angling downwardly.
[0023] A doorsill assembly 40 according to a first embodiment of
the present invention is best shown in FIGS. 3 and 4. Assembly 40
includes an elongated threshold member 42 disposed over and
adjustably connected to base 10. Assembly 40 also includes an
elongated weather cover panel 44, preferably constructed of an
aluminum alloy. Cover panel 44 is attached to base 10 so as to
overlie and extend from an exteriorly disposed edge 24a of second
strip 24 and interface wall 27. Cover panel 44 may include a rib 46
that is received in groove 29 of base 10. Cover panel 44 forms a
foot tread. An elongated gasket 48, preferably a compressible,
resilient vinyl gasket, is connected along an interior facing edge
portion 50 of cover panel 44, and extends along a narrow gap
between interface wall 29 and an exterior facing side 42a of
threshold member 42 to inhibit seepage of water therethrough.
[0024] A series of conventional, adjustable fasteners F connect
threshold member 42 to planar surface 26 of base. Accordingly,
planar surface 26 preferably includes a series of holes H for
receiving hardware F' operably associated with fasteners F.
Threshold member 42 may be adjustably connected to base 10 so that
the upper surface 42b of threshold member 42 conforms to the lower
edge of a door D in relatively close fitting relationship when door
D is in a closed position in a door frame (not shown).
[0025] Threshold member 42 may have an inverted U-shape
configuration in section so as to form an elongated, open chamber
52 between threshold member 42 and planar surface 26 of base 10. A
pair of compressible, resilient, waterproof end seal gaskets 54,
such as closed cell polymer gaskets, may be attached to opposite
ends of base using adhesive, although other suitable fastener
systems may be used.
[0026] Threshold member 42 is thus supported on planar surface 26
between upwardly extending wall 22a of first strip 22 and gasket
48. Threshold member 42 may include an elongated storm drain
channel 56 in upper surface 42b thereof, as described in U.S. Pat.
No. 5,179,804 to Young, the disclosure of which is incorporated
herein by reference. Accordingly, any water that seeps past the
weather strip of door D onto upper surface 42b will be collected in
storm drain channel 56. The water then migrates toward opposite
ends thereof, and downward through end slots in drain channel 56
and onto planar surface 26 of base 10, and thereafter migrates
inwardly into a pair of exteriorly extending weep channels 30
formed in base 10. Weep channels 30 may extend downwardly either
diagonally or in an arcuate shaped path to discharge water from
planar surface 26 out through slots 60 formed in a downwardly
extending portion of cover panel 44. In this way, water is expelled
from assembly.
[0027] A second embodiment of a doorsill assembly 70 is best shown
in FIGS. 5 and 6. Similar to assembly 40, assembly 70 includes a
base 72, a threshold member 74, and a cover panel 76. Base 72 is
nearly identical to base 10. Accordingly, base includes central
portion 12 with first and second strips 22, 24 secured thereto.
[0028] Threshold member 74 is similar to threshold member 42, but
does not include a storm drain channel. Cover panel 76 has a
slightly different configuration compared to cover panel 44, and
includes an upwardly extending, interiorly disposed wall 76a which
cooperates with a weather strip gasket 78 to seal the gap between
cover panel 76 and threshold member 74, such as the weather strip
gasket described in U.S. Pat. No. 6,484,446 to Young, the
disclosure of which is incorporated herein by reference.
[0029] While the disclosed banded doorsill base 10 has been
described in terms of various embodiments, it should be understood
that base 10 (or 72) may be used for any doorsill assembly.
Accordingly, the precise dimensions of central portion 12, and
strips 22, 24 may vary depending on the particular threshold member
and/or cover panel being used therewith. Furthermore, the precise
dimensions of base 10 and associated doorsill assemblies may vary
depending on the dimensions of the door frame in which the assembly
is being installed.
[0030] The present invention is also directed to a method of
forming banded doorsill base 10. A rectangular longitudinally
extending block of polymer material used to form central portion 12
is provided. Alternatively, a block of wood fiber-resin composite
material is provided. The polymer (or composite) block has a
generally rectangular configuration. First and second blocks of
wood are provided having generally rectangular configurations. The
wood blocks are wetted with water, such as by spraying a mist of
water thereon. Alternatively, the polymer (or composite) block is
wetted. A water-curing PUR adhesive is applied to first and second
opposite surfaces of the polymer (or composite) block, and the wood
blocks are aligned with and clamped against opposite sides of the
polymer (or composite) block. As an alternative to wetting the
blocks, the components may be clamped together in an environment
sufficiently humid to allow the water-curing PUR to fully cure.
Using a water-curing PUR, the components are preferably clamped
together for at least about 90 minutes to achieve 50% cure
strength.
[0031] After the components are cured, the resulting sandwiched
block of polymer (or composite) and wood is cut into rectangular
sections having a sufficient caliper and length to form banded
doorsill base 10. Each rectangular section is then machined to form
banded doorsill base 10, with its strips 22, 24, recessed planar
surface 26, and interface wall 27 being formed. The base 10 may
then be fitted with the cover panel, threshold member, etc.
[0032] It will be apparent to one of ordinary skill in the art that
various modifications and variations can be made in construction or
configuration of the present invention without departing from the
scope or spirit of the invention. It is intended that the present
invention cover all such modifications and variations, provided
they come within the scope of the following claims and their
equivalents.
* * * * *